<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>动态验证码1</title>

    <style>
               .code {
                        width: 100%;
                         margin: 0 auto;
                    }
                .input-val {
                                 width: 63%;
                                   background: #ffffff;
                                 height: 2.8rem;
                                  padding: 0 2%;
                                   border-radius: 5px;
                                   border: none;
                                   border: 1px solid rgba(0,0,0,.2);
                                  font-size: 0.9rem;
                              }
                #canvas {
                                   float: right;
                                    display: inline-block;
                                  border: 1px solid #ccc;
                                   border-radius: 5px;
                                    cursor: pointer;
                              }
             </style>
</head>
<body>
    <form>
        <div class="code">
            <input type="text" value="" placeholder="请输入验证码(不区分大小写)" class="input-val">
            <canvas id="canvas" width="100" height="43" ></canvas>
        </div>
        <div class="layui-form-item">
            <button lay-filter="login" class="layui-btn layui-block" lay-submit>登陆</button>
        </div>
</form>
</body>
<script type="text/javascript" src="js/jquery-3.3.1.js"></script>
</html>
<script>
    var show_num=[]
    $(function () {

        //生成验证码
        draw(show_num)
        //点击图片出发验证码刷新
        $("#canvas").on('click',function () {
            draw(show_num)
        })
        //点击登陆触发判断
        from.on('submit(login)',function (data) {
            var val=$('.input-val').val().toLowerCase();
            var num=show_num.join("");
            if(val==''){
                alert("空的")
                layer.msg("请输入验证码",{icon:7,time:2000},function(){})
            }else if(val==num){
                alert("验证成功")
                //调用登陆方法，向后台发送数据
            }else{
                //提示验证码错误
                alet("验证码错误")
                lay.msg("验证码有误",{icon:7,time:2000},function(){})
                //自动刷新验证码
                $(".input-val").val('')
                   draw(show_num)
            }
            return false;
        })

        //生成验证码
        function draw(show_num) {
            var canvas_width = $('#canvas').width();
            var canvas_height = $('#canvas').height();
            var canvas = document.getElementById("canvas");//获取到canvas的对象，演员
            var context = canvas.getContext("2d");//获取到canvas画图的环境，演员表演的舞台
            canvas.width = canvas_width;
            canvas.height = canvas_height;
            var sCode = "A,B,C,E,F,G,H,J,K,L,M,N,P,Q,R,S,T,W,X,Y,Z,1,2,3,4,5,6,7,8,9,0";
            var aCode = sCode.split(",");
            var aLength = aCode.length;//获取到数组的长度

            for (var i = 0; i <= 3; i++) {
                var j = Math.floor(Math.random() * aLength);//获取到随机的索引值
                var deg = Math.random() * 30 * Math.PI / 180;//产生0~30之间的随机弧度
                var txt = aCode[j];//得到随机的一个内容
                show_num[i] = txt.toLowerCase();
                var x = 10 + i * 20;//文字在canvas上的x坐标
                var y = 20 + Math.random() * 8;//文字在canvas上的y坐标
                context.font = "bold 23px 微软雅黑";

                context.translate(x, y);
                context.rotate(deg);

                context.fillStyle = randomColor();
                context.fillText(txt, 0, 0);

                context.rotate(-deg);
                context.translate(-x, -y);
            }
            for (var i = 0; i <= 5; i++) { //验证码上显示线条
                context.strokeStyle = randomColor();
                context.beginPath();
                context.moveTo(Math.random() * canvas_width, Math.random() * canvas_height);
                context.lineTo(Math.random() * canvas_width, Math.random() * canvas_height);
                context.stroke();
            }
            for (var i = 0; i <= 30; i++) { //验证码上显示小点
                context.strokeStyle = randomColor();
                context.beginPath();
                var x = Math.random() * canvas_width;
                var y = Math.random() * canvas_height;
                context.moveTo(x, y);
                context.lineTo(x + 1, y + 1);
                context.stroke();
            }
        }

        function randomColor() {//得到随机的颜色值
            var r = Math.floor(Math.random() * 256);
            var g = Math.floor(Math.random() * 256);
            var b = Math.floor(Math.random() * 256);
            return "rgb(" + r + "," + g + "," + b + ")";
        }
    })


</script>